Vitamins

VITAMINS
Hello! My name is ……. and I am going to speak about the vitamins. To begin this oral presentation, one question: What is a vitamin?
Someone wants to answer my question?
Ok, vitamins are organic substances that the body cannot manufacture and that are necessary for normal metabolism; only 10 such substances are known in the human being. If these substances are present in insufficientquantity, disease results.
Vitamins are classified as either water-soluble, meaning that they dissolve easily in water, or fat-soluble vitamins, which are absorbed through the intestinal tract with the help of lipids (fats). In general, water-soluble vitamins are readily excreted from the body. Each vitamin is typically used in multiple reactions and, therefore, most have multiple functions.
Inhumans there are 13 vitamins: 4 fat-soluble (A, D, E and K) and 9 water-soluble (8 B vitamins and vitamin C).
But I am going to speak about ten of these vitamins, these are their names:

THE ESSENTIAL VITAMINS

FAT- SOLUBLE | WATER-SOLUBLE |
Vitamin A | Vitamin C |
Vitamin D | Vitamin B complex: |
Vitamin K | * Thiamine |
| * Riboflavin |
| * Niacin |
| * Pyridoxine|
| * Cobalamin |
| * Folate |

VITAMIN A (RETINOL) Vitamin A is one of the fat-soluble vitamins. In herbivorous animals the carotenoid pigments, such as the carotenes of plants and vegetables, are converted into vitamin A in the intestine, absorbed, and subsequently stored in the liver.
Human beings acquire their supply either directly from the carotenoids in vegetable matter(carrots and green vegetables in general) or indirectly from animal or dairy produce.
CAUSE OF VITAMIN A DEFICIENCY: This is usually due to a deficient diet. This nutritional problem usually occurs in Indonesia, parts of Asia, India, the Middle East, and Latin America.
Vitamin- A deficiency does, however, occur as a complication of the malabsorption syndrome.
EFFECTS OF VITAMIN A DEFICIENCY:
TheeyeVitamin A forms an essential component of rhodopsin, a pigment in the rods of the retina. By absorbing light, rhodopsin initiates an electrical impulse that is transmitted to the brain and is interpreted as light. The first sign of vitamin-A deficiency, therefore, is night blindness. This way the conjunctival epithelium loses its mucus-secreting goblet cells and becomes keratinized, so that theeye becomes dry and subject to cracking and infection. The condition is called xerophthalmia.
TOXICITY OF VITAMIN A: Very large dose of vitamin A are toxic and can cause an increase in intracranial pressure with headache, blurring of vision, vomiting and drowsiness.
This effect has been described by Arctic explorers when they ate polar bear liver, which is a very rich source of vitamin A.VITAMIN D Vitamin D is present in all fat- containing animal products, but its richest source is cod-liver oil. Vitamin D is also formed in the skin by the action of ultraviolet light.
The main action of the vitamin is the maintenance of calcium balance by facilitating the absorption of calcium from the intestine. The effects of hypovitaminosis D are rickets and osteomalacia.
Hypervitaminosis Ddue to toxic doses of the vitamin or to an increased response to its action; there is hypercalcaemia and metastatic calcification. Vomiting, anorexia, nausea, constipation, and renal failure are the main clinical features.

VITAMIN K Vitamin K is widely distributed in vegetable and animal foods. It is also synthesized by bacteria in the gut. Vitamin K-deficiency may occur by disturbed intestinaluptake, by therapeutic or accidental intake of vitamin K-antagonists or, very rarely, by nutritional vitamin K deficiency.
The main clinical features are stomach pains; risk of massive uncontrolled bleeding; cartilage calcification; and severe malformation of developing bone or deposition of insoluble calcium salts in the walls of arteries.

VITAMIN E Vitamin E includes a group of fat-soluble...